1. Field of the Disclosure
The present invention relates generally to switching devices, and more particularly, to a solid state power switching module assembly having improved thermal performance.
2. Description of Related Art
Examples of electrical devices that have idle interconnected current paths include transformer tap switches, static voltage-ampere-reactive (VAR) compensators, and static transfer switches (“STS”). In these devices, either the power source or load are interconnected via solid state switch device modules, such as dual silicon controlled rectifier (“SCR”) modules. Based on system requirements, portions of the interconnected path remain idle and become active based on the operation of the SCR modules. For example, a STS is commonly used to switch between a primary and one or more alternate power sources in the event of failure or instability of the primary source. STSs are commonly used in applications that require continuity of power, such as in hospitals, and critical processes in both industrial and commercial settings. At the heart of the STS are dual SCR modules, which are solid state switch devices that have two SCRs connected in an inverse parallel configuration to control the AC current supplied to a connected load.
A typical SCR module emits approximately 1 watt of heat per ampere of current through the device when conducting current to a connected load. Depending on the load requirements, the heat generated by the device can be well over one kilowatt. Failure to properly dissipate the heat generated by the SCR module can result in a premature failure and/or reduced performance of the SCR module. Moreover, the SCR module is typically housed inside an enclosure with other temperature sensitive electronic devices, and thus the increased heat energy generated by the SCR module can damage and/or impede the performance of surrounding electronic devices. A thermal interface, such as a heat sink, must be provided to dissipate the heat generated by the SCR module. Because of the criticality of the STS and thus the importance of having properly operating SCR modules, there is a continued focus on finding ways to more effectively dissipate the heat generated by the SCR modules and reduce the temperature rise of the heat sink.
Heretofore, methods of increasing the heat dissipating capability of the heat sink have included using aluminum heat sinks with copper portions interspersed at critical locations on the heat sink, such as that disclosed in U.S. Pat. No. 3,766,977 to Pravda et al.; the use of fans to more actively circulate the SCR module's heat energy throughout the surrounding air; and using a cooling fluid medium applied to the heat sink and/or the SCR module. Moreover, it has been thought that the heat generated by a SCR module spreads readily from the hot, active SCR module to areas of the heat sink which are occupied by inactive cooler devices.
The present application addresses these shortcomings associated with the prior art.